code: def find_start_offset_last_n_lines_from_offset(
      file: io.BufferedIOBase,
      offset: int,
      n: int,
      block_size: int = BLOCK_SIZE,
  ) -> int:
      """
      Find the offset of the beginning of the line of the last X lines from an offset.
  
      Args:
          file: File object
          offset: Start offset from which to find last X lines, -1 means end of file.
              The offset is exclusive, i.e. data at the offset is not included
              in the result.
          n: Number of lines to find
          block_size: Block size to read from file
  
      Returns:
          Offset of the beginning of the line of the last X lines from a start offset.
      """
      logger.debug(f"Finding last {n} lines from {offset} offset")
      if offset == -1:
          offset = file.seek(
              0, io.SEEK_END
          )  # move file pointer to end of file
      else:
          file.seek(
              offset, io.SEEK_SET
          )  # move file pointer to start offset
  
      if n == 0:
          return offset
      nbytes_from_end = 0  # Number of bytes that should be tailed from the end of the file
      # Non new line terminating offset, adjust the line count and treat the non-newline
      # terminated line as the last line. e.g. line 1\nline 2
      file.seek(max(0, offset - 1), os.SEEK_SET)
      if file.read(1) != b"\n":
          n -= 1
  
      # Remaining number of lines to tail
      lines_more = n
      read_offset = max(0, offset - block_size)
      # So that we know how much to read on the last block (the block 0)
      prev_offset = offset
  
      while lines_more >= 0 and read_offset >= 0:
          # Seek to the current block start
          file.seek(read_offset, 0)
          # Read the current block (or less than block) data
          block_data = file.read(
              min(block_size, prev_offset - read_offset)
          )
          num_lines = block_data.count(b"\n")
          if num_lines > lines_more:
              # This is the last block to read.
              # Need to find the offset of exact number of lines to tail
              # in the block.
              # Use `split` here to split away the extra lines, i.e.
              # first `num_lines - lines_more` lines.
              lines = block_data.split(b"\n", num_lines - lines_more)
              # Added the len of those lines that at the end of the block.
              nbytes_from_end += len(lines[-1])
              break
  
          # Need to read more blocks.
          lines_more -= num_lines
          nbytes_from_end += len(block_data)
  
          if read_offset == 0:
              # We have read all blocks (since the start)
              break
          # Continuing with the previous block
          prev_offset = read_offset
          read_offset = max(0, read_offset - block_size)
  
      offset_read_start = offset - nbytes_from_end
      assert (
          offset_read_start >= 0
      ), f"Read start offset({offset_read_start}) should be non-negative"
      return offset_read_start
  
imports: import logging
  from typing import Optional, Tuple
  import concurrent.futures
  import ray.dashboard.modules.log.log_utils
  import ray.dashboard.modules.log.log_consts
  import ray.dashboard.utils
  import ray.dashboard.optional_utils
  from ray._private.ray_constants import env_integer
  import asyncio
  import grpc
  import io
  import os
  from pathlib import Path
  from ray.core.generated import reporter_pb2
  from ray.core.generated import reporter_pb2_grpc
  from ray._private.ray_constants import LOG_PREFIX_TASK_ATTEMPT_START, LOG_PREFIX_TASK_ATTEMPT_END
label_desc: Use image node_id 4 for calling a global function with example usage: find_start_offset_last_n_lines_from_offset(file, offset, n, block_size) and returns: offset_read_start, offset